Use text affinity to return correct accessible line boundaries.

content/browser/accessibility/browser_accessibility.h

Index: content/browser/accessibility/browser_accessibility.h
diff --git a/content/browser/accessibility/browser_accessibility.h b/content/browser/accessibility/browser_accessibility.h
index 18e6354547380c1570def5d0acd2f8c5d6e46f55..a72e562975e15ae7d60dde26bfa821877389d4bb 100644
--- a/content/browser/accessibility/browser_accessibility.h
+++ b/content/browser/accessibility/browser_accessibility.h
@@ -166,7 +166,8 @@ class CONTENT_EXPORT BrowserAccessibility {
   // Starting at the given character offset, locates the start of the next or
   // previous line and returns its character offset.
   int GetLineStartBoundary(int start,
-                           ui::TextBoundaryDirection direction) const;
+                           ui::TextBoundaryDirection direction,
+                           ui::AXTextAffinity affinity) const;
 
   // Starting at the given character offset, locates the start of the next or
   // previous word and returns its character offset.